2022-10-14-----2022-10-16

1.

#include<stdio.h>
#include<pthread.h>
#include<string.h>
#include<semaphore.h>

char s[]="1234567";
sem_t sem1,sem2,sem3;

void* callback1(void* arg){
	
	while(1){
		sem_wait(&sem1);
		printf("%s\n",s);
		sem_post(&sem2);
	}

	pthread_exit(NULL);
}


void* callback2(void* arg){
	int i=0;
	char temp=0;
	while(1){
		sem_wait(&sem2);
		for(i=0;i<strlen(s)/2;i++){
			temp=s[i];
			s[i]=s[strlen(s)-1-i];
			s[strlen(s)-1-i]=temp;
		}
		sem_post(&sem3);
	}

	pthread_exit(NULL);
}

void* callback3(void* arg){
	
	while(1){
		sem_wait(&sem3);
		printf("hello world\n");
		sem_post(&sem1);
	}

}

int main(int argc, const char *argv[])
{
	
	if(sem_init(&sem1,0,1)<0){
		perror("sem_init");
		return -1;
	}

	if(sem_init(&sem2,0,0)){
		perror("sem_init");
		return -1;
	}

	if(sem_init(&sem3,0,0)){
		perror("sem_init");
		return -1;
	}
	
	pthread_t tid1,tid2,tid3;

	if(pthread_create(&tid1,NULL,callback1,NULL)!=0){
		perror("pthread_create");
		return -1;
	}

	if(pthread_create(&tid2,NULL,callback2,NULL)!=0){
		perror("pthread_create");
		return -1;
	}

	if(pthread_create(&tid3,NULL,callback3,NULL)<0){
		perror("perror");
		return -1;
	}	

	pthread_join(tid1,NULL);
	pthread_join(tid2,NULL);

	sem_destroy(&sem1);
	sem_destroy(&sem2);
	sem_destroy(&sem3);
	
	return 0;
}

2.

#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<string.h>

int main(int argc, const char *argv[])
{
	
	int pfd[2];
	if(pipe(pfd)<0){
		perror("pipe");
		return -1;
	}
	printf("无名管道创建成功 r=%d  w=%d\n",pfd[0],pfd[1]);
	
	pid_t pid = fork();
		
	if(pid>0){
		char  buf[128]="";
		ssize_t res=0;
		while(1){
			bzero(buf,sizeof(buf));
			scanf("%s",buf);
			getchar();
			res=write(pfd[1],buf,sizeof(buf));
			if(res<0){
				perror("write");
				return -1;
			}
			printf("写入成功\n");
		}

	}else if(0==pid){
		char buf[128]="";
		ssize_t res=0;
		while(1){
			bzero(buf,sizeof(buf));
			res=read(pfd[0],buf,sizeof(buf));
			if(res<0){
				perror("read");
				return -1;
			}
			printf("读取数据成功\n");
			printf("%s\n",buf);
		}
	}else{
		perror("fork");
		return -1;
	}
	
	
	return 0;
}